Direct observation of the ultrafast energy transfer in a porphyrin and ruthenium dyad

The luminescence dynamics of a polypyridyl ruthenium Ⅱ Ru(phen)2(ip)]2+ and 5,10,15,20-tetraphenylporphyrin (H2TPP) dyad have been measured by using time-resolved fluorescence spectroscopy. The transient luminescent spectra of the dyad show an ultrafast energy transfer within 300 ps after pho-toexcitation of the Ru(phen)2(ip)]2+ at 453 nm. However, no energy transfer has been observed as the excitation wavelength is 400 nm, corresponding to the absorption peak of H2TPP. The origin of the energy transfer from Ru(phen)2(ip)]2+ to H2TPP has been analyzed according to the Forster energy-transfer theory.